Latest climate and biosphere modelling suggests that the length of time carbon remains in vegetation during the global carbon cycle – known as ‘residence time’ – is the key “uncertainty” in predicting how Earth’s terrestrial plant life – and consequently almost all life – will respond to higher CO2 levels and global warming, say researchers.

Carbon will spend increasingly less time in vegetation as the negative impacts of climate change take their toll through factors such as increased drought levels – with carbon rapidly released back into the atmosphere where it will continue to add to global warming.

Researchers say that extensive modelling shows a four degree temperature rise will be the threshold beyond which CO2 will start to increase more rapidly, as natural carbon ‘sinks’ of global vegetation become “saturated” and unable to sequester any more CO2 from the Earth’s atmosphere.

They call for a “change in research priorities” away from the broad-stroke production of plants and towards carbon ‘residence time’ – which is little understood – and the interaction of different kinds of vegetation in ecosystems such as carbon sinks.

Carbon sinks are natural systems that drain and store CO2 from the atmosphere, with vegetation providing many of the key sinks that help chemically balance the world – such as the Amazon rainforest and the vast, circumpolar Boreal forest.

As the world continues to warm, consequent events such as Boreal forest fires and mid-latitude droughts will release increasing amounts of carbon into the atmosphere – pushing temperatures ever higher.

Initially, higher atmospheric CO2 will encourage plant growth as more CO2 stimulates photosynthesis, say researchers. But the impact of a warmer world through drought will start to negate this natural balance until it reaches a saturation point.

The modelling shows that global warming of four degrees will result in Earth’s vegetation becoming “dominated” by negative impacts – such as ‘moisture stress’, when plant cells have too little water – on a global scale.

Carbon-filled vegetation ‘sinks’ will likely become saturated at this point, they say, flat-lining further absorption of atmospheric CO2. Without such major natural CO2 drains, atmospheric carbon will start to increase more rapidly – driving further climate change.

The researchers say that, in light of the new evidence, scientific focus must shift away from productivity outputs – the generation of biological material – and towards the “mechanistic levels” of vegetation function, such as how plant populations interact and how different types of photosyntheses will react to temperature escalation.

Particular attention needs to be paid to the varying rates of carbon ‘residence time’ across the spectrum of flora in major carbon sinks – and how this impacts the “carbon turnover”, they say.

The Cambridge research, led by Dr Andrew Friend from the University’s Department of Geography, is part of the ‘Inter-Sectoral Impact Model Intercomparison Project’ (ISI-MIP) – a unique community-driven effort to bring research on climate change impacts to a new level, with the first wave of research published today in a special issue of the journal Proceedings of the National Academy of Sciences.

“Global vegetation contains large carbon reserves that are vulnerable to climate change, and so will determine future atmospheric CO2,” said Friend, lead author of this paper. “The impacts of climate on vegetation will affect biodiversity and ecosystem status around the world.”

“This work pulls together all the latest understanding of climate change and its impacts on global vegetation – it really captures our understanding at the global level.”

The ISI-MIP team used seven global vegetation models, including Hybrid – the model that Friend has been honing for fifteen years – and the latest IPCC (Intergovernmental Panel on Climate Change) modelling. These were run exhaustively using supercomputers – including Cambridge’s own Darwin computer, which can easily accomplish overnight what would take a PC months – to create simulations of future scenarios:

“We use data to work out the mathematics of how the plant grows – how it photosynthesises, takes-up carbon and nitrogen, competes with other plants, and is affected by soil nutrients and water – and we do this for different vegetation types,” explained Friend.

“The whole of the land surface is understood in 2,500 km2 portions. We then input real climate data up to the present and look at what might happen every 30 minutes right up until 2099.”

While there are differences in the outcomes of some of the models, most concur that the amount of time carbon lingers in vegetation is the key issue, and that global warming of four degrees or more – currently predicted by the end of this century – marks the point at which carbon in vegetation reaches capacity.

“In heatwaves, ecosystems can emit more CO2 than they absorb from the atmosphere,” said Friend. “We saw this in the 2003 European heatwave when temperatures rose six degrees above average – and the amount of CO2 produced was sufficient to reverse the effect of four years of net ecosystem carbon sequestration.”

For Friend, this research should feed into policy: “To make policy you need to understand the impact of decisions.

“The idea here is to understand at what point the increase in global temperature starts to have serious effects across all the sectors, so that policy makers can weigh up impacts of allowing emissions to go above a certain level, and what mitigation strategies are necessary.”

###

The ISI-MIP team is coordinated by the Potsdam Institute for Climate Impact Research in Germany and the International Institute for Applied Systems Analysis in Austria, and involves two-dozen research groups from eight countries.

They put in “real” data and get what-if scenarios showing total drought with a 4C temperature rise and plants not functioning? And we are modeling “how the plant” grows? How does one get data on photosynthesis where one size fits all plants? Sounds like most of their “data” are computer output with pre-determined end points. Are the results more believable when you have a super computer in a model comparison project?

German and Austrian taxpayers who are funding this sort of alarmist nonsense from the Potsdam Institute for Climate Impact Research in Germany and the International Institute for Applied Systems Analysis in Austria should feel savagely aggrieved. One glance at the chart of peer reviewed literature would tell one that CO2 remains in the atmosphere for less than 10 years, not 100 years. The IPCC might as well claim 1,000 years and make a real meal of it all.

I’m with talldave2, being in Denver, we’ve experience lows last week of minus 10 and an expected high today of 60. With a swing of 70 degrees in about 7 days, it is hard to imagine we’d notice a thing with a 4 degree difference.

Actually now that I read it again this makes perfect sense, they just forget a term.

“Researchers say that extensive modelling shows a four4+/-25 degree temperature rise will be the threshold beyond which CO2 will start to increase more rapidly, as natural carbon ‘sinks’ of global vegetation become “saturated” and unable to sequester any more CO2 from the Earth’s atmosphere.”

Temperatures were about 3.0C to 4.0C higher in the Miocene from about 15 Mya to 20 Mya. The Carbon cycle does not appear to have been any different since CO2 was about 250 ppm to 280 ppm in the period (although there a few random estimates at 400 ppm but these are just a few random estimates amongst hundreds of others in the 250 to 280 range).

Wait a minute, all the discussion of residence time has referred to CO2 in the atmosphere, not plants. In the very first sentence they have re-defined this as “the length of time carbon remains in vegetation during the global carbon cycle – known as ‘residence time’ -“. This is a bait and switch as non-one is concerned with residence time in plants, only in the atmosphere.

And even more junk when they use 4 degrees as the end of the world scenario, but the effect on plants is the supposed widespread drought that this 4 degree rise creates. Really? Such a rise in temperature is going to remove water vapour from the atmosphere? Despite the fact that such an increase would release a great deal of frozen water from glaciers and get it into liquid form where it will evaporate easier? The simplistic idea that warmer equals drier is the complete opposite of the basic CAGW meme that CO2 effect in the atmosphere is amplified by the increased water vapour which it causes.

No, pile of junk from the first to the last. No basis in physical or biological fact (as the people who have pointed out how well plants grow at a wide range of temperatures have already pointed out).

When a single molecule of carbon dioxide containing an atom of light carbon (carbon-12) is released into the atmosphere from fossil fuel burning, it remains in the atmosphere for about 5 years. During that 5 year period it has a 50% chance of being absorbed by the ocean’s surface every 12 months. So, after 5 years, there is only a 3.5% chance that that same molecule still exists.

of course, when a carbon dioxide molecule is absorbed by a liquid at saturation (the surface of the ocean is operating at saturation) concentrations, the liquid immediately outgasses another molecule of CO2 so that it stays in partial pressure equilibrium with the atmospheric concentration.

so, yes, the individual molecule is removed, but it is replaced by another molecule, so the essential increase in the atmospheric concentration of CO2 caused by burning fossil fuel is preserved, for about 1000 years (the time it takes for the deep water ocean convection to produce a single overturn.

“talldave2 says:
December 16, 2013 at 1:04 pm
My area experiences a 100-degree annual temperature swing. The notion 4 degrees would have any noticeable effect on vegetation is laughable.”

The answer is yes and no – many plant species have quite large geographical ranges. Some plant species have very narrow geographical ranges due to limits in ability to live at temps over or below certain levels. Most citrus trees have northern limit whereby they can survive once temps go below a certain level.
The norway/red pines common in north central minnesota and wisconsin have a very narrow range whereby the species has a very definite upper and definite lower temp limits. The species only has a north-south range of 200 or so miles. So a change of 4 degrees would be significant for that species and other species that have narrow ranges. Most all other plant species would be significantly less affected by 4 degrees

” Hybrid – the model that Friend has been honing for fifteen years – and the latest IPCC (Intergovernmental Panel on Climate Change) modelling. …. and that global warming of four degrees or more – currently predicted by the end of this century – marks the point at which …..”

So all this is based on known to be broken models referred to by the IPCC and especially the hot end of the range that estimate 4C by 2100.

We know we’re wrong but we’ll just keep on repeating it long enough maybe people won’t notice the snow drifts in the middle east and will start to believe us. Got to give credit for trying.

“The ISI-MIP team is coordinated by the Potsdam Institute “. AH! right , now I see. Ramsdorf behind this by any chance? Sounds like his kind of fairy tale numbers.

Rob Potter says:
December 16, 2013 at 1:29 pm
Wait a minute, all the discussion of residence time has referred to CO2 in the atmosphere, not plants. In the very first sentence they have re-defined this as “the length of time carbon remains in vegetation during the global carbon cycle – known as ‘residence time’ -”. This is a bait and switch
>>>>>>>>>>>>>>>>>

Yeah, I noticed that too. Plus, their whole analysis depends on uptake of CO2 by the biosphere becoming saturated due to a “moisture deficit) in the mid latitudes. Well, most of the biosphere actually lives in the oceans, which in turn comprise 2/3 of the earth surface. So, “mid latitudes” is a small portion of 1/4 of the earth’s surface… in other words, diddly squat. Not to mention that a “moisture deficit” actually increases the rate at which energy is lost to space as water vapour accounts for 80+ % of the greenhouse effect in the first place, so increased aridity actually = global cooling. If you’ve ever been in a desert at night, it cools off very fast because there is no water vapour and so once the sun goes down it gets cold fast. Then there’s the problem of assuming a sensitivity that is way higher than actual evidence supports and extrapolating from what amounts to a fiction with no basis in reality. I didn’t read the paper, but expect they also didn’t factor in positive feedback from increased biosphere activity in places currently frozen (ie they cannot claim both that the ice caps will melt AND that nothing will grow there because it is too cold).

This paper is so sad that mocking it gives it more credibility than it deserves.

jai Mitchel: says: “.. of course, when a carbon dioxide molecule is absorbed by a liquid at saturation (the surface of the ocean is operating at saturation) concentrations, the liquid immediately outgasses another molecule of CO2 so that it stays in partial pressure equilibrium with the atmospheric concentration.”

Garbage, very little of the ocean is in equilibrium with the atmophere, where did you get that from? Oh, you just made it up because it sounded right. Sorry.

Why don’t we take a close look at what vegetation and biodiversity were like the last time it was 4 degrees Celsius warmer than now? Say, in the early Miocene? Were things really as bad as these guys forecast?

Wait a minute, all the discussion of residence time has referred to CO2 in the atmosphere, not plants. In the very first sentence they have re-defined this as “the length of time carbon remains in vegetation during the global carbon cycle – known as ‘residence time’ -”. This is a bait and switch as non-one is concerned with residence time in plants, only in the atmosphere.
====
There’s no reason why you can’t define a “residence time” for the terrestrial reservoir but it does sound like an almost deliberate attempt to reframe the question.

In essense I think you’re right. The ocean is the major sink/source and the volume of exchange with the oceans is far greater than that with land based biosphere. While attempts to better understand any part of the system should be helpful in building the overall picture, it’s the ocean interaction that will be determinant.

Garbage, very little of the ocean is in equilibrium with the atmophere, where did you get that from? Oh, you just made it up because it sounded right. Sorry.

I actually said,the surface of the ocean is operating at saturation

the surface of the ocean is, indeed, “very little of the ocean” as you say.

equilibrium concentration at the surface of the ocean is based on the solubility of CO2 in that particular location, at a given temperature and atmospheric concentration, the solubility of CO2 in the surface layer will indeed be at saturation.

You are confusing the terms “solubility” (from your link) with “saturation”, these are two very different terms.

The theory of plant residence time would seem to be eminently testable. Some greenhouses, some CO2, temperature controllers, and plants. And see what happens, every 30 minutes if you want. It’l be right there in front of you.

Is Potsdam going to pay for that, or perhaps a computer model is cheaper and more moldable to ones’ expectations.

That might be more impressive if it were supported by any evidence at all from historical geology. It is not. No model that does not handle the Phanerozoic changes can seen as serious in any fashion other than as a bad example. No evidence of catastrophic effects due to CO2 changes exists on earth. The only evidence of effects on plant productivity in historical geological data show that profound increases in atmospheric CO2 accompany increased biological productivity. It is vastly more likely that halving atmospheric CO2 would be more damaging than a doubling. Available empirical evidence indicates that a drop to 180 ppm would be very seriously damaging for agricultural and for natural productivity. Gardening advice generally recommends CO2 enrichment of anywhere from double current “natural” levels to as much as 1,500 ppm in green houses. Roses for example like high levels of CO2 >1,000 ppm.

It isn’t going to warm anywhere near 4° which makes the entire paper a big s0-what. We will likely experience two cool PDOs this century and a solar minimum of some unknown degree. Chances are it won’t be any warmer in 2100 then it is right now, and it could be cooler.

The long term warming impact of the MOC is likely to end during this century given the cycle length over the last 2000 years. At that point the planet begins slowly cooling.

Meanwhile, in Michigan, our lake froze much earlier than usual as temperatures have been -10 to -20 degrees below average this month. That, of course, is consistent with *global warming*. It is also consistent with releasing more CO2 into the atmosphere which will lead to more cold weather consistent with *climate change*. But we are doing our part by increasing the number of land-based wind turbines that kill off predatory birds and bats while causing psychological problems in humans. We’d use solar power, but the Great Lakes keeps this region pretty cloudy for during the winter and when the sun shines it is only for 10 hours a day. Regardless, we are looking forward to helping the third world countries and friends of our president by paying large carbon taxes. That about covers it.

Warming a mostly water covered object (Earth) increases precipitation, with more evaporated from the oceans onto land, for not land alone warms.

That happened during the warm lush age of the dinosaurs and, to a lesser degree, when measured precipitation slightly increased by ~ 2% (not decreased) over the 20th century.

In contrast, during the cold last glacial maximum, there was “there was much less closed forest and more desert than at present,” for deserts are made by lack of precipitation: an area can even be cold but yet a desert if arid enough. http://www.esd.ornl.gov/projects/qen/nerc.html

The water usage efficiency of plants also goes up enormously with elevated CO2.

The above is aside from how, in reality, there is no coming 4 degree warming anyway, rather incoming cooling.

Just watched a good portion of the Discovery Channel (Canada/UK) production “Earth from Space”. It was actually pleasantly short on the doom being perpetuated by the human species in the planet – in favour of describing the many complex mechanisms that have created climate stability – and thus protected life – for several billion years.

What struck me most from the show relative to the “4 degrees of doom” post was the dominant role of plankton (called the “most important plant life on this planet”) in the carbon cycle – and thus how silly it is to think that the follies of the human species could ever have any significant ffect. Plankton are attributed with a full 50% of the O2 regeneration of the planet. Thus it follows that the life and death of this diminutive species has a similarly large role in locking up carbon. The Discovery Channel folks say the deposits of dead plankton that rain down on the ocean floor are up to a kilometre thick.

The Cambridge study focuses on land and drought with nary a mention of the role of the remaining 70% of the planet (by area – volume notwithstanding). Oops.

No droughts to worry about under water. And warmer water ought to create real “plankton party?”

Nominees for the STOTY award? (Siloed Thinking Of The Year)

PS. Despite its obligatory reference in the final minutes of the show to the impact of man – including the production of “gases” (anthropogenic CO2 was not specifically identified) – I don’t see how anyone could watch “Earth from Space” and think we are not but a bit player in the carbon equation. Note the show was reproduced by PBS for its Nova series – available on YouTube – sorry I don’t know how to insert the link.

Your link simply propagates the myth that CO2 in the atmosphere just happens to have been finely balanced for centuries with no apparent mechanism enforcing that balance, as though it were just an accident of nature. This is a narrative, an assertion of how you would like to imagine things to be, and which may sound nice and pleasant to you and some others, but it is not proven, is in fact highly unlikely on its face, and is bereft of physical insight.

Nature just does not work that way. If there are no powerful forces opposing one another, then an equilibrium does not become established until a fundamental limit has been reached. At best, in such a situation, a natural system will wander randomly and far afield in search of a boundary, like the particles suspended in a fluid which undergo Brownian motion. This hypothesis, according to which a delicate balance has been established for an extended time interval until upset by a tiny external forcing, is fundamentally self-contradictory.

I predict that a four degree rise will increase rainfall and vegetation density. Result will be an increase in atmospheric Oxygen causing animal life to increase in size and longevity. Over time, larger populations of larger animals will increase atmospheric CO2 further increasing vegetation density, etc., etc., and so on.

Then, something Milankovitchian will happen causing the climate to turn sharply colder. Many animal species will die along with a large percentage of the vegetation. That’s what my models show.

I am pretty certain that different definitions of ‘residence time’ are being mixed up here (again).

What is being talked about – the time a given CO2 molecule stays in the atmosphere before being exchanged with one from the ocean and/or biosphere? Or the time that would be required to reach a new equilibrium if we stopped emitting CO2 now?

As I understand the paper, it is about terrestrial and not aquatic plant carbon dioxide consumtion. I guess aquatic autotrophs don’t count. Last time I took an oceanography class it was mentioned that 80% of the oxygen we breathe comes from aquatic autotrophs. I would presume that this means that at least 80% of the CO2 is consumed by aquatic autotrophs.

The caption under the image states that human caused CO2 only stays in the atmosphere about 5 years. While this is technically true, it doesn’t mean that the concentration of CO2 goes down after 5 years (as many on this site have suggested). The CO2 that goes into the surface of the ocean indeed switches out with another CO2 molecule that was previously in the water under saturation.

The ISI-MIP team is coordinated by the Potsdam Institute for Climate Impact Research in Germany and the International Institute for Applied Systems Analysis in Austria, and involves two-dozen research groups from eight countries.

Good, so we can blacklist the whole bunch when their forecast falls flat.

William,
Name calling does not change the fact the planet resists (negative feedback) rather amplifies (positive feedback) forcing changes by an increase or decrease of planetary clouds in the tropics.
Dr. Chisty’s graph presented at the congressional investigation, under oath (i.e. he did not make it up), supports that assertion, as does Lindzen and Choi’s analysis of top of the atmosphere radiation Vs short term surface ocean temperature changes, supports the assertion that the planet resists rather than amplifies forcing changes.http://www-eaps.mit.edu/faculty/lindzen/236-Lindzen-Choi-2011.pdf
On the Observational Determination of Climate Sensitivity and Its Implications
Richard S. Lindzen1 and Yong-Sang Choi2

If the planet resists rather than amplifies forcing changes, there is no extreme AGW crisis to solve. You guys have however created a crisis that will destroy the economic foundation of the US and the EU, if you are not stopped. ‘Green’ energy is a very, very, expensive scam that makes our countries less and less able to compete. The path we are on will lead to Spanish syndrome, massive unemployment and the gutting of entitlements.

Read the following books ‘Power Hunger: The Myths of “Green” Energy and the Real Fuels of the Future’, by Robert Bryce (CH4 as a bridge to nuclear) and ‘Super Fuel, Thorium, The Green Energy Source for the Future’, by Richard Martin. Ignoring facts does not change facts.
It should be noted that James Hansen and friends who have read and thought about this issue in addition to name call are advocating a massive move to nuclear power. We currently have a dysfunctional government, a group of fanatics who are absolutely incorrect about AGW, and a large group of special interesting leaches feeding of the mistakes of our government policies. You guys are a dangerous distraction from the real problems our countries face.

4 degrees is meaningless in agriculture. Each country has its own indiginous plants that are well able to withstand this increase. It is when you plant non indiginous plants that there could be a problem.

Africa has idiginous and nutritious plants well able to withstand a 4 degrees increase. Scarcity of water is always a problem but non idiginous plants cause havoc in this area in hot countries.

A lovely look at nutritious plants well able to withstand droughts.
[PDF]Africa’s Indigenous Crops – Worldwatch Institutehttp://www.worldwatch.org/system/files/NtP-Africa‘s-Indigenous-Crops.pdf
Like many other crops indigenous to Africa, the eggplant is easy to grow and high yielding, … meet the rising demand for crops across the African continent.

I get so excited about African plants thought I would give you a little taster,

Beyond its uses as a staple food, parts of the baobab tree such as its bark are used as cooking fuel for stoves, kilns for firing pottery, and ovens. In dry areas, the extremely large, hollow stem holds a valuable water resource, as it can store as much as 10,000 liters of water for many months. Local populations often build shelters and keep livestock inside baobab trunks.

“As the world continues to warm, consequent events such as Boreal forest fires and mid-latitude droughts will release increasing amounts of carbon into the atmosphere – pushing temperatures ever higher.

Initially, higher atmospheric CO2 will encourage plant growth as more CO2 stimulates photosynthesis, say researchers. But the impact of a warmer world through drought will start to negate this natural balance until it reaches a saturation point”

To get the results they wanted, these clowns had to make several several bad assumptions.
1. That global temperatures will increase much more than what any credible evidence shows.
2. That droughts and boreal forest fires will increase, again with no legit evidence
3. That increasing temperatures and CO2 will adversely effect plants when studies show that plants do better under warmer temperatures when CO2 levels are doubled.

Elevated CO2 Helps Reduce the Negative Impacts of High Temperatures on Plant Growth:
“the optimum temperature for plant growth and development has typically been found to rise right along with the air’s CO2 content. For a 300-ppm increase in atmospheric CO2, for example, theoretical and observational studies have shown that the optimum temperatures of most C3 plants rise by approximately 5°C for such a CO2 increase. This rise in optimum temperature is even larger than the rise in air temperature predicted to result from the greenhouse effect of such a CO2 increase. Consequently, it is clear that a CO2-induced warming would not adversely affect the vast majority of Earth’s plants; for fully 95% of them are of the C3 variety”

Increasing CO2 without question increases vegetative growth. This increase, also leads to bigger contributions from plant respiration to low level moisture during the growing season at mid latititudes. This factor decreases droughts.

Deserts are in drought all the time. It gets very hot there during much of the year/Summer. What has happened in deserts when we increased CO2 in the real world?…………

I am sure I have read a bigger bunch of malarkey, but it must have been a while ago as I don’t recall it. Why does anyone let this sort of “my computer model says it is so” heifer dust get into a journal? (well it would be ok in a sci-fi journal)

And to the guys arguing about how long some CO2 that went into the atmosphere because I burned some steaks on the grill — none of you know how long that bit of CO2 will stay in the atmosphere and stop pretending you do. No one does. I do know that 400 ppm is a trace gas and that man’s minor addition to that is a trace of a trace.

Stupidity annoys me. All this talk of 4 degree rise has no reality because there is no warming. They like to call the current cessation of warming a “hiatus” which it is not. There is more carbon dioxide in the air than ever before but there has not been any greenhouse warming this is supposed to cause for the last fifteen years. The absence of greenhouse warming, the life blood of the alleged “anthropogenic global warming” for this length of time is sufficient to tell me as a scientist that it does not exist. That wonderful idea that Svante Arrhenius presented, of the doubling of carbon dioxide changing the climate, is simply wrong. But this is not all. The actual documented cessation of warming has lasted 33 years, not 15 years because because we must add an 18 year stretch from the eighties and nineties. The reason you don’t know about it is that official temperature curves covered it up with a bogus “late twentieth century warming.” Doing research for my book “What Warming?” I proved that this warming did not exist and even put a warning about it into the preface of the book. Nothing happened for two years but then the big three of temperature – GISTEMP, HadCRUT, and NCDC, decided , in unison, not to show this warming any more. What they did was to line up their data for this period with satellites which do not have this fake warming. It was done secretly and no explanation was given. The explanation is that my book exposed their scam. What we have now is two periods of no-warming, The two stretches of no-warming are separated only by the super El Nino of 1998 and its accompanying step warming. It is that step warming, caused by the warm water carried over by the super El Nino and not by CO2, that raised all twenty-first century temperatures above the twentieth. Hansen and his acolytes keep claiming that carbon dioxide did it which shows how ignorant they are of real climate science.

If co2 drops to 200 to 300 ppm then human beings quit breathing . If co2 drops to 160 to 180 ppm then vegetation starts dying and mammals also starts dying. .Compliments of the scientific ignorance of CAGW groups.

Aside from the obvious residence time plug, they also have the water cycle effect inverted. Cool air holds less moisture, leading to droughts, while warm holds more and increases precipitation. Witness the “Carboniferous” climate.

The planet has mostly been completed forested for the past, let’s say, 180 million years (since Pangea broke apart and the large deserts in its interior disappeared).

Then 2 things happened.

C4 grasses evolved about 24 million years ago. This then established a new vegetation biome on Earth which allowed a more active Carbon Cycle to develop and CO2 levels dropped below 280 ppm, for perhaps the very first time.

The planet remained completely forested (well except for Antarctica). In fact, 10 million years ago, 50 different species of Apes lived in these forests. It really was the “planet of the Apes” at this time. 50 species of large mammals is domination.

Then, 8 million years ago, something happened which changed the Earth’s climate so that there was less precipitation and the forests started to die back in colder regions and in dryer regions. Perhaps it got that just little bit colder. Instead of +2.0C, it was only +1.5C.

C4 grasses expanded exponentially and we have the appearance of savanna grasslands and open areas for the first time since Pangea. C4 grasses are more efficient in dryer and hotter areas and replace the C3 trees and bushes. One of those 50 species of Ape decided to develop upright walking to navigate the open savanna regions and we evolved as a result although it took another 7.5 million years.

Then the ice ages started up about 2.7 million years ago. Precipitation fell during the glacial cycles so that grassland and tundra and desert became more common on the planet than forested areas. At the last glacial maximum, only the US southeast was forested. The rest was grassland, or glacier or tundra or desert. CO2? 185 ppm.

CO2 seems to have played no part in these changes at all. It is evolution/Carbon Cycle and precipitation which falls as it gets colder (and rises as it gets warmer). There are certain latitudes which develop deserts if a large landmass is present (Sahara, Pangea monster deserts) but this is geographic/a rotating planet with an atmosphere/low temperature related).

Regarding the carbon residence time. It is actually irrelevant because carbon dioxide is not warming the world (see my other comment). But rather than trust modeling and hypothetical warming that will not happen, we can use observations. There are two sets of observations that are relevant. The first is the measured decay of atmospheric carbon-14 following the cessation of atmospheric nuclear testing in the twentieth century. These observations give a carbon residence time of 10 years or less. The second data source is the Keeling curve. It is sensitive enough to show the yearly wiggle caused by loss and regrowth of leaves on deciduous trees. One result based on this wiggle gives a residence time of about seven years. Both of these could be revisited and refined if the global warming establishment can spare some of the hundreds of millions of dollars they waste on trying to prove a non-existent warming. Forget about the effect of the hypothetical changes predicted by their models that are worthless.

Just watched a good portion of the Discovery Channel (Canada/UK) production “Earth from Space”. It was actually pleasantly short on the doom being perpetuated by the human species in the planet – in favour of describing the many complex mechanisms that have created climate stability – and thus protected life – for several billion years.
—
Note the show was reproduced by PBS for its Nova series – available on YouTube – sorry I don’t know how to insert the link.

“The researchers say that, in light of the new evidence, scientific focus must shift away from productivity outputs – the generation of biological material – and towards the “mechanistic levels” of vegetation function, such as how plant populations interact and how different types of photosyntheses will react to temperature escalation.”

For the one Bazillionth time, you must understand that model runs, simulations, do not and cannot produce evidence.

Instead, you should say that what you know about biomass absorption of CO2 on planet Earth allows you to create scenarios on supercomputers and that the scenarios show that four degrees of warming is the tipping point, given that your assumptions in the scenarios are reasonable on scientific grounds. Simulations cannot produce scientific grounds. It follows, then, that your first task is to present arguments to the effect that your assumptions are reasonable on scientific grounds.

Great geological arm waving (and it fits the geological history). There is so much more to this wonderful planet than CO2, but at some point (as in diamond mines and life on earth as we know it) the stuff is important. Just not so much in controlling the temperature of the Earth.

“””Today is the 350th day of 2013 and an incredibly urgent time for our climate. In just the last few weeks, we’ve seen the terrible and heartbreaking costs of massive climate disruption worldwide and at our backdoor. We’re up against incredibly well-funded industries that want to keep business as usual. Yet business as usual will mean we destroy the planet.

I have friends asking me: is it too late? No. We can build a better world for our children. But we are the last generation that has a chance to address the climate crisis and this must be our legacy. That’s where you come in. You understand what is at stake and how little time we have to reverse this trend. This year, we surpassed unprecedented atmospheric carbon dioxide levels of 400 ppm for the first time when the consensus among climate scientists is that the safe upper limit is 350 ppm.

Today, on the 350th day of 2013, can you chip in $350, $100, $35 or more? We are less than $7,000 away from our December 31st goal of $75,000 to launch a new climate action initiative.”””

I appreciate you trying to explain co2 residence time but your link is really basic stuff and super general. For example, what happens to the co2 I am exhaling in my house? I highly doubt any of these molecules is making it to the ocean, based upon where I live. And the co2 isn’t just lingering in the air, otherwise I would be dead. I’m just not seeing the long residence time, how do you justify the IPCC deviating from the peer reviewed literature on it? Secondly, we know throughout geologic history that deserts had once been tropical paradise such as the Sahara. The late Ordovician period had an atmospheric co2 concentration around 4400ppm and there were glaciers, the GAT at this point was similar to today’s. So if the earth can do that naturally, how can you possibly believe the manmade influence is more powerful than the natural? If you think humanity can prevent things like this in the future, why aren’t you promoting terraforming?

BW2013 says:
December 16, 2013 at 5:35 pm
Today, on the 350th day of 2013, can you chip in $350, $100, $35 or more? We are less than $7,000 away from our December 31st goal of $75,000 to launch a new climate action initiative.”””
===============
And what is this climate initiative you might ask? Why of course to get our asses out of this cold winter weather and off to some tropical paradise where we can spend the day’s sipping Mai-tai’s with the local hotties. Please give generously.

BW2013 says:
December 16, 2013 at 5:35 pm
This year, we surpassed unprecedented atmospheric carbon dioxide levels of 400 ppm for the first time when the consensus among climate scientists is that the safe upper limit is 350 ppm.
===========
Too late. Were all dead. Might as well kill yourself.

Zeke writes “I wrote a brief article a few years back that might be helpful:”

Well I’m pretty sceptical about the paper your article is based on, Zeke. Its widely believed that the ocean provides around half the O2 and therefore marine based photosyntheesis is a very large part of the cycle.

fwiw the wiki states “The tiny marine cyanobacterium Prochlorococcus was discovered in 1986 and accounts for more than half of the photosynthesis of the open ocean”

And yet your paper says the following about the ocean’s role in absorbing CO2 wrt life “An implicit scheme is used to compute CO2 gas exchange over the annual time step, as biological activity alters the carbon chemistry of surface waters.”

With no supporting reference. What “implicit scheme” one might ask? And how does it vary with temperature wrt that biological activity? The whole paper pretty much ignores life as far as I can see and concentrates on the chemical processes involved. Its no wonder it predicts a slow sequestration rate…

TimTheToolMan says:
December 16, 2013 at 6:09 pm
The whole paper pretty much ignores life as far as I can see and concentrates on the chemical processes involved. Its no wonder it predicts a slow sequestration rate…
==========
You hit the nail on the head. Microscopic life calls the shots. It is why CO2 sequestration varies as a function of the annual excess. Inorganic models predict that sequestration varies as the the total excess and assume that it is simply coincidence that sequestration remains firmly fixed at 1/2 of annual excess, even though annual excess is taking off like a rocket with China’s growth. Life predicts that sequestration will vary as the source inputs, and the cumulative excess will simply be co-incidence.

“The researchers say that, in light of the new evidence”— What evidence is that? The article was discussing what it clearly stated was a model. I’m not a jurist, but I’ve some experience as a Legal Officer when I was still in the Navy, and a model is NOT evidence. Were that the case, I could “prove” someone committed a crime with a re-enactment. Rot. A Model demonstrates how I believe my theory works. It is an explanation. It is NOT evidence of ANYTHING except my own pet aflatus.

To go a bit further, while the model apparently looks at vegetation as if it’s the ONLY thing in the biosphere that reacts with CO2, it ignores all sea life and it’s interactions with CO2 during this increase in temperature, it ignores all chemical reactions at the increased temperatures with the Earth’s crust, it doesn’t even admit that there are other things to consider outside of this pet theory about plants. I don’t recall any studies that show that vegetation has behaved this way in the past, and they reference none in the article. Did they research any to corroborate their model?

I gotta ask: is it just me, or does it appear to anyone else that these guys are getting desperate and grasping at straws?

How can they have such a detailed discussion on CO2 and plants while totally ignoring that the vast majority of the CO2 is dissolved in the oceans and would certainly cook out a fair bit with a four deg C increase in temperature? The oceans would swamp out any plant-based changes. These people are discussing the color of a mouse’s fur while a snake is busy eating it.

My results: Time constant of 20 years, halflife of 14 years in the past several years. Also, I have looked at the bomb test results before, and it appears to me that ocean sinking decreased after the warming acceleration in the 1970s.

Not that I see atmospheric lifetime of CO2 increasing from 14 years halflife soon, now that we have a warming hiatus that appears to me as likely to continue for roughly 20 more years. Also, I don’t see ocean sinking stopping due to saturation, since solubility of a gas in a liquid varies directly, usually close to proportionately, with the concentration of the gas above the liquid. The atmospheric halflife of CO2 appears to me likely to increase once the sun bottoms out from a likely short and deep dip in activity, maybe in the 2030s. However, I still see halflife of atmospheric CO2 in excess of equilibrium with top ocean waters not getting much past 20 years.

As for equilibrium with ocean far enough down to not have had CO2 content significantly increased, that is longer. I remember having calculated a few years ago something in the 3-5 decade class.

Rather than taking their output from questionable computer models, why don’t they build their own (CEAS) Controlled Environment Agriculture Center to see what would happen to their plants if they raised the temp 4 degrees and decreased the artificial rainfall. The stomata in plants have amazing abilities to compensate.

What you are missing is the effect of living things in the ocean waters you suppose to be in equilibrium according to Henry’s law. The ocean surface and atmosphere are not in equilibrium. Based on lots of measurements from instrumentation towed behind ships at several meters depth it was thought that atmospheric pCO2 was 7 u atm higher than the ocean, indicating saturation Takahashi et al 2012. Calleja_et al_GBC_2013 showed that there is an average pCO2 gradient of 14 u atm between 5m and the surface, 11 of which are in excess of temperature according to Henry’s law. These measurements were taken in the Mediterranean and North Atlantic and tropical Atlantic oceans, not where you expect upwelling to be pushing CO2 into the air.

The atmosphere Ocean interface is a magical place. More energy is cycled through this interface than the earth receives from the sun. An analogous nano carbon cycle also takes place across it, the magnitude of which we will never know until we quit building models that pretend it is in equilibrium and get our butts out there and measure it.

Re: My recent above posting: I am now estimating that atmospheric lifetime of CO2 beyond 300 PPMV is about 50 years in terms of halflife. The 14 years I got is atmospheric lifetime in terms of halflife of the portion of the CO2 that is past the level that is in equilibrium with the concentration of dissolved CO2 in the ocean surface waters. I expect this shorter figure to be similar to the bomb test results, since ocean surface water CO2 was not yet greatly elevated above that of ocean hundreds of meters down in the decade after the bomb tests.

These guys need to come and have a go at clearing my garden here in the tropics. If you leave it for a minute, I swear the grass grows an inch. If you leave for a month’s holiday, you need to borrow a neighbour’s tractor just to get to the house….

“Its important to distinguish between the average residence time of a single molecule and the time needed to remove an accumulated stock of carbon.”

Yes, very important. The time needed to remove an accumulated stock of atmospheric CO2 is much shorter than the residence time of a single molecule. The atmosphere is in direct contact with the oceans after all. Any increase in the atmospheric pCO2 will drive it into the oceans very quickly. There’s nothing to stop it. Oceans contain much more than the atmosphere and they will hardly notice it.

“The modelling shows that global warming of four degrees will result in Earth’s vegetation becoming “dominated” by negative impacts – such as ‘moisture stress’, when plant cells have too little water – on a global scale.”

Had they used a Ouija board for that, everyone would call them liars.

But somehow when you use a computer for the same purpose everyone suddenly assumes you’re an honest man.

I don’t doubt that their model shows what they say it shows. I just doubt that it is the only model one could make. An infinte number of models that all fit the past equally well, with wildly different outcomes in the future, are possible.

As always, this model HAS NO VALUE because the PREDICTIVE SKILL has not been demonstrated.

This whole discussion is slightly absurd. Why the focus on the biosphere alone ?

We do NOT even know which biological OR geophysical processes dominate globally in carbon sequestration and mobilization. This lack is a slight problem when trying to get some handle on what is going on, no ?

One thing I will point out is how likely it is that the amount of carbon sequestered in carbon-containing-sedimentary-rock-deposits is much larger than organic deposits. But we don’t have very good numbers for any of this.

This research seems to have been invented by geographers. Surely biologists/botanists know more about this sort of thing.

They know more, but they are now under pressure to ration the release of their existing knowledge and to use externally imposed guidelines in the acquisition of new knowledge. I am sure (I sure hope) the Plant Sciences department next door will not publish anything as outrageous as the geographers at Clare just did, but I know the plant science folks are not indifferent to the outcome. They can now mention CO2, “environment” and “impacts” a dozen times per page in their grant applications. They use the funds granted this way to do real science (most of them do, most of the time, anyway), while Clare’s notoriety gets them the majority of student applications in Cambridge. Win-win. There is no disincentive in sticking one’s head out in a “progressive” sort of way. If anything goes wrong at Cambridge (unlikely), there are always careers to be made at the Grantham Institute.

“talldave2 says: December 16, 2013 at 1:04 pm
My area experiences a 100-degree annual temperature swing. The notion 4 degrees would have any noticeable effect on vegetation is laughable.”

The answer is yes and no – many plant species have quite large geographical ranges. Some plant species have very narrow geographical ranges due to limits in ability to live at temps over or below certain levels. Most citrus trees have northern limit whereby they can survive once temps go below a certain level.
The norway/red pines common in north central minnesota (sic) and wisconsin <sic) have a very narrow range whereby the species has a very definite upper and definite lower temp limits. The species only has a north-south range of 200 or so miles. So a change of 4 degrees would be significant for that species and other species that have narrow ranges. Most all other plant species would be significantly less affected by 4 degrees"

Narrow range for Red Pine? Nonsense in one fashion, bizarrely stated in another.

Red/Norway pine is a very popular tree for planting and is easily available from local nurseries. Hard up for one? Easy, get one at Musser Forests.

Red pine is planted over a much greater geographical range now. Stands and landscape Norway pines are planted further south even in zones 6-7. It may not thrive as well, but t grows. So much for definite upper and lower limits.

The Forest Service’s page linked above describes how Red pine germinates best after a forest fire. The FS also mentions how the Red Pine migrated to survive previous climate changes.

Perhaps you are referring to the original Native distribution area? Though even that original distribution area is much larger than a 200 miles north south range.

Trees are far older than man and given the antics of the alarmists and MSM, perhaps wiser than many humans. Trees are definitely more adept at this climate stuff.

i thought that ”residence time” was the time that CO2 spent in the ATMOSPHERE not in plants or has Cambridge rewritten the GHG theory? Residence time in plants would depend on plant species for a start and probably hundreds of other inputs but not how much CO2 we put into the system since our proportion is but 3% of the total.
Seems this paper was written by Harry Potter.

The diagram in the article is bogus. The figures other than that of the IPCC are estimates of residence time (a.k.a. turnover time – the average length of time a molecule of CO2 remains in the atmosphere before being taken up by the oceans or terrestrial biosphere), the figure for the IPCC is an estimate of ADJUSTMENT time (the characteristic timescale on which atmospheric CO2 levels adapt to changes in sources or sinks). These are not the same thing at all, and whoever produced the diagram clearly didn’t bother to check their facts. The IPCC actually give an estimate of about 4 years for residence (turnover) time, which is completely in accordance with the other studies.

The residence (turnover) time depends on the volume of the fluxes out of the atmosphere, which are very large, so the residence time is short. The adjustment time depends on the difference between the fluxes into and out of the atmosphere, which is small (compared to anthropogenic emissions), which is why the adjustment time is much longer.

Please, in the interests of climate skeptics, stop promulgating this misrepresentation of the science. It is easily demonstrated to be incorrect, just look up “lifetime” in the glossary of the IPCC WG1 AR4 report (it appears on page 948).

So when co2 was 1,200ppm the world plunged into catastrophe? Nay, nay and thrice nay. What a load of modelling horse poop. Here is what I read above [my emphasis].

“Latest climate and biosphere modelling suggests…..Researchers say that extensive modelling shows a four degree temperature rise…..part of the ‘Inter-Sectoral Impact Model Intercomparison Project’ (ISI-MIP)…..seven global vegetation models, including Hybrid – the model…..and the latest IPCC (Intergovernmental Panel on Climate Change) modelling……While there are differences in the outcomes of some of the models, ….”

And they have the gonads to mention the IPCC modelling.

Here are some real observations of the past. Check out the temperatures.

Abstract – James L. Crowley – 12 November 2010Effects of Rapid Global Warming at the Paleocene-Eocene Boundary on Neotropical Vegetation
Temperatures in tropical regions are estimated to have increased by 3° to 5°C, compared with Late Paleocene values, during the Paleocene-Eocene Thermal Maximum (PETM, 56.3 million years ago)………eastern Colombia and western Venezuela. We observed a rapid and distinct increase in plant diversity and origination rates, with a set of new taxa, mostly angiosperms, added to the existing stock of low-diversity Paleocene flora. There is no evidence for enhanced aridity in the northern Neotropics. The tropical rainforest was able to persist under elevated temperatures and high levels of atmospheric carbon dioxide,…….http://www.sciencemag.org/content/330/6006/957
doi: 10.1126/science.1193833
———————–Abstract – Carlos Jaramillo et. al. – May 2013Global Warming and Neotropical Rainforests: A Historical Perspective
…Our compilation of 5,998 empirical estimates of temperature over the past 120 Ma indicates that tropics have warmed as much as 7°C during both the mid-Cretaceous and the Paleogene….. The TRF did not collapse during past warmings; on the contrary, its diversity increased. The increase in temperature seems to be a major driver in promoting diversity.http://www.annualreviews.org/doi/abs/10.1146/annurev-earth-042711-105403
doi: 10.1146/annurev-earth-042711-105403

Co2 is plant fertilizer even at 800ppm and more. We have such a long way to go and I very much doubt we will ever hit 800ppm, but I hope we do. Enter the projectionists: If China and India’s co2 output follows their present trajectory………blah, blah. Would you care to say the same about the USA? Things change!

Good graphic! This 4C threat, like the 2C threat, is presented as a major disturbance to the climate system. A system that copes every year with about a 4C variation in mean temperature as it orbits round the sun.

Bill Illis says:
December 16, 2013 at 1:23 pm
Temperatures were about 3.0C to 4.0C higher in the Miocene from about 15 Mya to 20 Mya. The Carbon cycle does not appear to have been any different since CO2 was about 250 ppm to 280 ppm in the period (although there a few random estimates at 400 ppm but these are just a few random estimates amongst hundreds of others in the 250 to 280 range).

On the contrary we had the evolution of C4 plants to combat such a change.

Edim, the figure given in the article above is clearly incorrect. The IPCC say that residence time is about 4 years, not 50-200 years, anyone who doesn’t believe me can look it up for themselves in the IPCC report, I have given the page number to make it as easy as I can. Unlike Ferdinand, I do not have infinite patience to explain these misunderstandings again and again. I wrote a journal paper on this topic in the hopes it might go somewhere towards ending the discussion of this canard on climate blogs, which only serves to discredit the skeptic community by its repetition. You can find the paper here:

Abtract
A recent paper by Essenhigh (Essenhigh, R. H. Energy Fuels 2009, 23, 2773−2784) (hereafter ES09) concludes that the relatively short residence time of CO2 in the atmosphere (5–15 years) establishes that the long-term (≈100 year) rise in atmospheric concentration is not due to anthropogenic emissions but is instead caused by an environmental response to rising atmospheric temperature, which is attributed in ES09 to “other natural factors”. Clearly, if true, the economic and political significance of that conclusion would be self-evident and indeed most welcome. Unfortunately, however, the conclusion is false; it is straightforward to show, with considerable certainty, that the natural environment has acted as a net carbon sink throughout the industrial era, taking in significantly more carbon than it has emitted, and therefore, the observed rise in atmospheric CO2 cannot be a natural phenomenon. The carbon cycle includes exchange fluxes that constantly redistribute vast quantities of CO2 each year between the atmospheric, oceanic, and terrestrial reservoirs. As a result, the residence time, which depends upon the total volume of these fluxes, is short. However, the rate at which atmospheric concentrations rise or fall depends upon the net difference between fluxes into and out of the atmosphere, rather than their total volume, and therefore, the long-term rise is essentially independent of the residence time. The aim of this paper is to provide an accessible explanation of why the short residence time of CO2 in the atmosphere is completely consistent with the generally accepted anthropogenic origin of the observed post-industrial rise in atmospheric concentration. Furthermore, we demonstrate that the one-box model of the carbon cycle used in ES09 directly gives rise to (i) a short residence time of ≈4 years, (ii) a long adjustment time of ≈74 years, (iii) a constant airborne fraction, of ≈58%, in response to exponential growth in anthropogenic emissions, and (iv) a very low value for the expected proportion of anthropogenic CO2 in the atmosphere. This is achieved without environmental uptake ever falling below environmental emissions and, hence, is consistent with the generally accepted anthropogenic origin of the post-industrial increase in atmospheric carbon dioxide.

The adjustment time cannot be shorter than the residence time, if you think that is the case, you do not understand the meanings of these terms. The residence time depends on the rate CO2 is taken out of the atmosphere. However the rate at which an excess of CO2 is removed from the atmosphere also depends on the rate at which it is being added by the natural environment, which is why adjustment time is inevitably longer.

The graphic lists the graph’s source as Lawrence Solomon’s “The Deniers,” but perhaps it would help the readership to know (1) whether the red bar was in the original and (2) how that particular graphic was chosen to accompany the post without explanation of its precise relevance.

Dikran, when you add CO2 to the atmosphere, you increase the pCO2 in the atmosphere and therefore create a gradient in pCO2 (atmosphere/oceans). What is the mechanism that prevents the CO2 influx into oceans? The oceans can hardly notice the increase, since they contain MUCH more.

I will repeat again – the adjustment time must be shorter than the residence time. It might take a long time to remove a molecule (it has to be present at the exchange interface) , but how can it take long time to equalize partial pressures? It makes no sense.

Dikran, I don’t know – I only know that there is so much confusion. The consensus scientists themselves are not precise at all and mix the terms.

My point is that the adjustment time is even shorter than the atmospheric ‘life time’ of an individual molecule, simply because the atmosphere is in direct contact with the oceans, while an individual molecule is not.

That the dynamic equilibrium of the biosphere(Ie time to equilibrium after a pertubation) is very long is counter to evidence along many lines.

1. Each year 1/2 the excess CO2 is taken up by something.
2. The ocean cannot be in equilibrium with a rising atmospheric partial pressure of CO2 (Only can be in equilibrium with a constant partial pressure CO2)
3. The Ocean does not exchange one for one, even with a constant partial pressure of CO2, some of the CO2 is removed to the lower ocean, or consumed by the plant-life, bacteria life in the ocean, losses if you like.
4. Observationally plant productivity varies quickly as CO2 partial pressure rises, not slowly. One would expect photosynthesis, vegetation productivity, vegetation density, and vegetation range to adapt to CO2 changes within a few years.

Some of the issues.

It has already been mentioned that warmer climates reduce drought.
Desert areas are not generally determined by temperature but rather by continental positions relative to the dominant circulations.
Temperature rise is known to be biassed to the minimums, for example the minimum temperatures are reduced. Moving from polar regions to the equator we generally see less extreme climates, with the temperature ranges narrowing to 10 degrees near the equator. Maximum temperatures at any given latitude (where the max is significantly above freezing) are likely to fall with global warming while minimums rise (more than the maxes fall). This known pattern (due to water evaporation) is counter to the assertion that droughts will emerge from warming.
As temperatures rise vegetation patterns would move northward, (in the Northern Hemisphere) Vegetation wont die out, it will move based on the new distribution of rainfall, and the relevant circulations controlling rainfall. As Vegetation moves further northward where the largest land masses are I would expect an increased sinking effect due to higher vegetation density and extended growth range of vegetation (in the far north). Can’t say much for the south because there aren’t many land-masses in the right place for range expansion

All of this ignores the fact that raising the temperature by 4 Degrees would imply an energy absorption by CO2 to be increased by about 12% from 85% absorption to 97% absorption (assuming that all the 33 degree rise above blackbody of the atmosphere has to do with GHGs (which it is not)) at which point the energy absorbed by CO2 would be 97% of incident. This requires many doublings of CO2 to achieve. – IE 4 degrees of warming is practically impossible to achieve, if I recall correctly by the time CO2 is dense enough to cause 4 degrees of warming, combustion will be impossible because O2 levels will be too low to support combustion.

O.K., so you can’t be bothered to check whether basic information is correct or not, I have to say that is not what I would call skepticism, but perhaps it explains how such canards manage to survive in climate discussions on blogs.

I have already explained why adjustment time cannot possibly be less than residence time, but you have ignored that explanation, and just repeated yourself, so there is little point in me continuing the disucssion.

DirkH says:
December 17, 2013 at 12:55 am
An infinte number of models that all fit the past equally well, with wildly different outcomes in the future, are possible.
===========
that is the difference between Victorian age physics and modern physics. classical physics holds that there is only 1 future for any given past. modern physics holds there are a near infinite number of futures for any single past.

while this may seem an abstract notion, it has profound consequences when trying to predict the future. the models are trying to deal with the future as though classical physics was correct. it isn’t. at a fundamental level the models do not and cannot represent the future.

bobl says:
December 17, 2013 at 5:29 am
3. The Ocean does not exchange one for one, even with a constant partial pressure of CO2, some of the CO2 is removed to the lower ocean,
============
the oceans are continually turning CO2 into limestone. Ca + CO2 + O2 ===> CaCO3

via plate tectonics, the earth is continually turning limestone into hydrocarbons, recycling calcium back to the oceans.

Latest climate and biosphere modelling suggests that the length of time carbon remains in vegetation during the global carbon cycle – known as ‘residence time’ – is the key “uncertainty” in predicting how Earth’s terrestrial plant life – and consequently almost all life – will respond to higher CO2 levels and global warming, say researchers.

IPCC defines Mean Residence Time thus:

Turnover time (T) (also called global atmospheric lifetime) is the ratio of the mass M of a reservoir (e.g., a gaseous compound in the atmosphere) and the total rate of removal S from the reservoir: T = M / S. For each removal process, separate turnover times can be defined. In soil carbon biology, this [Turnover time, T] is referred to as Mean Residence Time. Bold added, AR4, Glossary, p. 948.

However, IPCC also reports another flux not included in Figure 7.3, nor specified as being included in the vegetation reservoir:

The total amount of CO2 that dissolves in leaf water amounts to about 270 PgC/yr [GtC/yr], i.e., more than one-third of all the CO2 in the atmosphere. Citations deleted, TAR, ¶3.2.2 Terrestrial Carbon Processes, ¶3.2.2.1, p. 191.

Since the leaf water reservoir is uncertain, the residence time for vegetation cannot be immediately fixed. However, leafwater is a flux to the atmosphere which increases S_atm to 485 GtC/yr without affecting M_atm, so it reduces T_atm to 1.6 years.

“Carbon dioxide (CO2) is an extreme example. Its turnover time is only about four years because of the rapid exchange between the atmosphere and the ocean and terrestrial biota. However, a large part of that CO2 is returned to the atmosphere within a few years. Thus, the adjustment time of CO2 in the atmosphere is actually determined by the rate of removal of carbon from the surface layer of the oceans into its deeper layers. Although an approximate value of 100 years may be given for the adjustment time of CO2 in the atmosphere, the actual adjustment is faster initially and slower later on.”

So, the figure given in the article above mixes the two terms, the turnover and the adjustment time.

You say:

“The adjustment time cannot be shorter than the residence time, if you think that is the case, you do not understand the meanings of these terms. The residence time depends on the rate CO2 is taken out of the atmosphere. However the rate at which an excess of CO2 is removed from the atmosphere also depends on the rate at which it is being added by the natural environment, which is why adjustment time is inevitably longer.”

I don’t understand what you’re trying to say. Increasing the carbon dioxide concentration of the atmosphere will cause the ocean to take up more carbon dioxide. Since the oceans contain much more, they will hardly notice it. Individual molecules are another story, they have to wait for their turn to be taken up.

The adjustment time is shorter than the turnover time. What is there to prevent the CO2 flux into the oceans when you increase the atmospheric pCO2? This is fast, even the consensus agrees, but they claim that the oceans are “getting full”. That’s laughable.

The model speculations above about doom are a pack of lies. The paleo recored contradicts this for the neotropical forests which warmed up to 7C. They not only persisted, they thrived. What about vegetation as you head towards the poles? Some will shrivel, while warm climate vegetation comes in and takes their place. On balance, no catastrophe. Why don’t these modellers take an honest look at the past and actually carry out long term, empirical based experiments without going into immediate extremes such as 5,000ppm in 24 hours or 15C maintained rise for tundra plants in 12 hours.? ;)Previous references

Abstract
Alexander W. Cheesman & Klaus Winter – Journal of Experimental Botany – July 19, 2013Growth response and acclimation of CO2 exchange characteristics to elevated temperatures in tropical tree seedlings
….. Seedlings of 10 neo-tropical tree species from different functional groups were cultivated in controlled-environment chambers under four day/night temperature regimes between 30/22 °C and 39/31 °C. Under well-watered conditions, all species showed optimal growth at temperatures above those currently found in their native range. While non-pioneer species experienced catastrophic failure or a substantially reduced growth rate under the highest temperature regime employed (i.e. daily average of 35 °C), growth in three lowland pioneers showed only a marginal reduction….
doi: 10.1093/jxb/ert211

Edim, so you would agree that the figure at the top of the article is misleading as it suggests that the IPCCs estimate of residence time is at odds with a range of other studies, when in fact it isn’t, and this fact is very easily verified? Do you not find it odd that nobody seems to have questioned, and that it seems to have been automatically accepted as the truth?

The fact that you are still concentrating on the sinks and completely ignoring the natural sources, shows that you are still not listening to the explanation already given.

Your explanation is wrong and so is IPCC. The adjustment time is shorter than the turnover time of an individual CO2 molecule. If you increase the atmospheric pCO2, you create a gradient and CO2 will be taken by the oceans. The oceans are not ‘getting full’, not even close.

Letter To Nature
Stephanie Pau et. al. – Nature Climate Change – 23 May 2013Clouds and temperature drive dynamic changes in tropical flower production
…..Here we quantify cloudiness over the past several decades to investigate how clouds, together with temperature and precipitation, affect flower production in two contrasting tropical forests. Our results show that temperature, rather than clouds, is critically important to tropical forest flower production. Warmer temperatures increased flower production over seasonal, interannual and longer timescales, contrary to recent evidence that some tropical forests are already near their temperature threshold4, 5. Clouds were primarily important seasonally, and limited production in a seasonally dry forest but enhanced production in an ever-wet forest. A long-term increase in flower production at the seasonally dry forest is not driven by clouds and instead may be tied to increasing temperatures. These relationships show that tropical forest productivity, which is not widely thought to be controlled by temperature, is indeed sensitive to small temperature changes (1–4°C) across multiple timescales.
doi:10.1038/nclimate1934

Edim wrote “Your explanation is wrong” sadly this is all too common in discussion of climate on blogs. If you want to be able to say that an explanation is wrong, you need to actually engage with the explanation provided, rather than steadfastly refusing to address the key element, which is that you need to consider the sources as well as the sinks to understand adjustment time.

Reuters – 6 February 2013Amazon forest more resilient to climate change than feared – study
(Reuters) – The Amazon rainforest is less vulnerable to die off because of global warming than widely believed because the greenhouse gas carbon dioxide also acts as an airborne fertilizer, a study showed on Wednesday……..

“I am no longer so worried about a catastrophic die-back due to CO2-induced climate change,” Professor Peter Cox of the University of Exeter in England told Reuters of the study he led in the journal Nature. “In that sense it’s good news.”

Cox was also the main author of a much-quoted study in 2000 that projected that the Amazon rainforest might dry out from about 2050 and die off because of warming.

Slowly but surely people are seeing the light. There will be no catastrophic warming. This 4C is taken from the Brother Gimm fairy tales. Climate sensitivity has booted the 4c to the kerb. Let’s just move along?

4 degree rise will end vegetation ‘carbon sink’Latest climate and biosphere modelling suggests that the length of time carbon remains in vegetation during the global carbon cycle – known as ‘residence time’ – is the key “uncertainty” in predicting how Earth’s terrestrial plant life – and consequently almost all life – will respond to higher CO2 levels and global warming, say researchers.

How good are the models they used? I hope they fine tuned their models.

One look at the Keeling curve shows that a 100 year residence time is wrong. The annual net May to October CO2 draw-down seen in the curve is about 1.7%. The curve is dominated by northern hemisphere plant growth, and by absorption in a cooling southern ocean, but also includes a smaller counteracting cycle from plants in the southern hemisphere, plus a smaller release from a warming northern ocean. As such, 1.7% is a gross underestimate of the annual atmospheric CO2 exchange. If we assumed for the sake of argument that the Keeling curve captured 100% of the annual CO2 exchange, it would imply a 40 year residence half-life as a strict upper bound. Given the C-14 data implies a 10 year residence half-life, the Keeling curve serves as independent confirmation that the number is reasonable, and that it captures a remarkable 25% of the actual CO2 exchange.

ferdberple says:
December 17, 2013 at 6:13 am
“that is the difference between Victorian age physics and modern physics. classical physics holds that there is only 1 future for any given past. modern physics holds there are a near infinite number of futures for any single past.

while this may seem an abstract notion, it has profound consequences when trying to predict the future. the models are trying to deal with the future as though classical physics was correct. it isn’t. at a fundamental level the models do not and cannot represent the future.”

It has nothing to do with mechanistic determinism versus Quantum uncertainty. Rather, the models do not and cannot, for reasons of complexity, be a one to one mapping of reality. Would take a computer with at least as many atoms as the modeled system, for obvious reasons. They model statistically. It is possible to create good statistical models, but predictive skill has to be demonstrated. As always these people fail to do so because they just don’t care. I have in fact never seen one single instance where researchers of the climate complex did it. All you get is a Trust us we’re scientists.

DirkH says:
December 17, 2013 at 8:01 am
“It is possible to create good statistical models, but predictive skill has to be demonstrated. ”

I mean that in a general sense; an example would be a statistical model for the behaviour of a gas in a container. Whether it is possible for the Earth’s climate remains to be seen, as no attempt has been demonstrated to be successful by now. The existence proof has not been delivered.

Edim, you clearly are not considering all, as otherwise your argument would include a mention of the sources as well as the sinks, but it has not done so at any point. Do yourself a favour and get a book on the carbon cycle and read it (David Archer’s primer is a good start), and learn the basics, rather than having the hubris to think that you know better than the leading scientists.

The model and these assumptions don’t take into account how the 4c would be spread around the planet because if they did we would have very different outcomes.This kind of rise affects many different local climates differently. The deserts aren’t there because of warm temperatures, but due to weather circulation patterns unable to give precipitation to those areas. The colder the planet, the increased risk these weather circulation patterns fail to deliver due to lack of water vapour in the atmosphere..

With the planet warming 4c in past for example the tropics warm less than 1c, mid latitudes about 2-3c and the poles around 7-9c. Therefore little change would occur in the tropics, mid-latitudes benefit from a modest warming and the poles greatly benefit from major warming. Hence, plants would flourish in a warmer world where leaves would grow bigger with higher CO2 levels, higher water vapour and more warmth. Vegetation in sub Arctic would spread up towards the poles, so the model doesn’t even behave like the real world, no wonder it is wrong.

yes about 1/2 of all CO2 emitted by human sources is removed each year, leaving about half to increase the earth’s concentration an additional 1% above the previous years concentration.

so, say 2 molecules of CO2 are emitted by human sources in a year. within that year 1 will go away and the other will be absorbed and another emitted by a saturated ocean surface within about 5 years.

over about 1000 years, the thermohaline current will have caused enough upwelling of low-saturation CO2 water (that descended before the industrial revolution at 270ppmv) This, and other CO2 fertilizer and expanding woodland growth into the boreal areas will cause a slow and growing sink to carbon dioxide.

However, this will take a very very very long time to return to 270 ppmv

Dikran, I don’t know – I only know that there is so much confusion. The consensus scientists themselves are not precise at all and mix the terms.

My point is that the adjustment time is even shorter than the atmospheric ‘life time’ of an individual molecule, simply because the atmosphere is in direct contact with the oceans, while an individual molecule is not.

Define what you mean by “adjustment time”. The key issue is how long it will take for the ‘pulse’ of CO2 added over the past century or so (and over then next century or so) to be removed from the atmosphere should CO2 from fossil fuel burning cease.

Currently CO2 atmospheric CO2 concentrations are about 400 ppm, i.e. about 120 ppm has been added over the past 150 years or so. The question then is this: If all fossil fuel burning ceased tomorrow how long would it take before the excess 120 ppm is removed. from the atmosphere.
It would certainly take longer than 5 years.

In theory, it could take thousands of years to remove the lot but, in practice, most would probably be gone within 100 years. 50% would be re-absorbed within about 40 years and around 37% (1/e) would remain in the atmosphere after about 55 years.

I believe Lubos Motl has performed a very rough calculation to show that it would take at least 60 years before the total excess was removed. This assumed that the current rate at which the excess is absorbed (~2 ppm per year) remains constant leading to the simple calculation that T = 120/2 = 60 years. However, the rate of ‘excess re-sequestration’ is likely to be a function of the actual excess so will reduce as the excess declines. Some form of negative decay function might, therefore, be more appropriate.

jai mitchell says “yes about 1/2 of all CO2 emitted by human sources is removed each year” and then later “over about 1000 years, the thermohaline current will have caused enough upwelling of low-saturation CO2 water …”

When I see that kind of “logic” being applied, I cringe. But its all too common amongst the warming enthusiasts to embrace non-logic to support their views.

Edim says:
December 17, 2013 at 8:26 am
Dikran, all is considered. The time needed to remove individual molecules is longer than the time needed for removal of the partial pressure gradient at the air-water interface. Think!

It is you who needs to think, it appears that you don’t understand the mechanism of gas exchange with the ocean! The atmosphere and ocean are in near dynamic equilibrium, CO2 molecules are constantly being dissolved in the ocean and constantly being outgassed at an approximately equal rate, the ratio between the two reservoirs is given by Henry’s law. Thus individual molecules which dissolve are replaced by ones from the ocean so the lifetime of individual molecules in the atmosphere is necessarily less than the time for removal of the excess. If the rate of solution is Rs and the rate of dissolution Rd the individual gas molecules are depleted at Rd whereas the excess is depleted at Rd-Rs.

The ratio is given by Henry’s Law, which states that the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. By increasing partial pressure you increase the amount of a given gas that dissolves. The oceans contain much more and are hardly influenced by this ‘excess’ amount. This removal is very fast, as you say the system is in near dynamic equilibrium. Of course we have to agree on how near.

What do you think is the main natural CO2 sink, oceans or the biosphere (or something else)? What causes the removal of over 50% of human CO2 emissions (in average with much temperature dependent year-to-year variability). Why do the natural sinks ‘expand’?

The atmosphere weighs about 5 quadrillion tons. Let’s call it 5 thousand million million tons.

Of this weight, roughly 400 parts per million are carbon dioxide. So we scrap one of the millions, and multiply the 5 thousand by 400. Answer, 2 thousand thousand million tons or 2,000 billion tons.

Roughly.

According to Trenberth et al, biomass absorbs a little more than 400 billion tons a year and emits about the same.

The turnaround time of the “average” CO2 particle is a bit under 5 years. QED.

jai mitchell earlier tried to cloud the waters somewhat with sophistry. Unfortunately his or her argument is fallacious because he/she is invoking a special meaning of the word “residence,” in fact she/he is more or less redefining the word, giving it a meaning opposite to that which it is intended to have.

What mitchell was trying to say is that the gap between biomass absorption and emission is so small, that even if the human contribution ceased immediately, the CO2 content of the atmosphere would decline by perhaps one per cent in the next year.